Integrated magnetic resonance imaging (MRI) and Linear Accelerators (LINAC) system image guidance during radiotherapy has become increasingly important and has gained wide application during the last years. The aim of the system is to deliver a precise radiation dose to a selected target within the interior of the body based on diagnostic quality MR images. Typically, a LINAC source is placed on a rotating gantry about the magnet of an MRI apparatus and the magnet is designed such that the LINAC rotates in a zero-field region of the magnet.
The target position where the beam is directed at is an essential parameter that affects the tissue destruction along the beam and overall treatment safety. An efficient positioning control and usage of such system may be necessary.
EP 2624915 A1 discloses an image guided radiation therapy system and shielded radiofrequency detector coil for use therein. The international application WO2014/044635 discloses a LINAC guided by a magnetic resonance imaging system. The magnetic resonance imaging system has a radio frequency coil with fiducial markers. These markers are imaged, their position evaluated and position of the radio frequency coil calculated.